edu.rice.hj.api

Interface HjPlace

All Known Implementing Classes:

PlaceImpl

public interface HjPlace

The place construct in HJ provides a way for the programmer to specify affinity among async tasks. A destination place may optionally be specified for where the task should execute. The number of places remains fixed during program execution; there is no construct to create a new place after the program is launched.

A place is an abstraction for a set of worker threads. The management of individual worker threads within a place is not visible to an HJ program.

Data locality can be controlled by assigning two tasks with the same data affinity to execute in the same place. An optional at clause can be specified on an async statement or expression of the form, asyncNbAt(place-expr, body), where place-expr is a place-valued expression. This clause dictates that the child async task can only be executed by a worker thread at the specified place. If the at clause is omitted, then the child task is scheduled by default to execute at the same place as its parent task. The main program task is assumed to start in place 0. Each task has a designated place. If a program only uses a single place, all async tasks just run at place 0 by default. The value of a task's place can be retrieved by using the method call, here(). The current release of HJ supports a flat partition of tasks into places.

Author:

Shams Imam (shams@rice.edu)

Method Summary

Modifier and Type	Method and Description
int	id() Returns the id of this place.
HjPlace	nextPlace()
int	numPlaces()
HjPlace	place(int id)
HjPlace	prevPlace()

Method Detail

id

int id()

Returns the id of this place. Home place has an id of zero.

Returns:

the id of this place.

place

HjPlace place(int id)

Returns:

the place with given id.

numPlaces

int numPlaces()

Returns:

the number of configured places.

nextPlace

HjPlace nextPlace()

Returns:

the next place using circular indexing of the set of places.

prevPlace

HjPlace prevPlace()

Returns:

the prev place using circular indexing of the set of places.